There isn’t very much documentation of
small-unit tactics and patrol techniques in the 1860’s.

However, Dennis H. Mahan was Professor of
Tactics and Engineering at the United States Military Academy, during the 1830s
and 1840s.

While Mahan is better known for his writings for the
application of engineering and fortifications to the art of war, his writings
and classes included discussion of tactics and techniques for the maneuvering of
small bodies of troops. His students included some famous names of the
American Civil War such as George McClellan, Joe Johnson, and Robert E. Lee.

What is not common knowledge are the thoughts
and subsequent teachings from one of his first works about offensive maneuver.
D.H. Mahan wrote

"An Elementary Treatise
on Advanced -Guard, Out-Post, and Detachment Service of Troops and the Manner of
Posting and Handling Them in the Presence of an Enemy."

This manual was written by Professor Mahan in
his early years at West Point (1837) before earthworks and fortifications
dominated his writings and theory.

There are seven chapters in this manual which
covers the following: -Manner of Placing & Handling Troops; -Positions,
Advanced-Guard and Advanced-Posts; -Reconnaissance; -Detachments; -Convoys; and
Surprises & Ambuscades.

Below are two items from the manual.

320. The
main duties of a patrol are to find the enemy if in the neighborhood; gain a
good idea of his position and strength; to make out his movements, and to bring
in an accurate account of his distance from the out-posts of their own force;
and the character of the ground between the position occupied by the respective
forces.

321. From the nature of these duties, it is
evident that both officers and men, for a patrol, should be selected with
especial reference to their activity, intelligence, and the aptitude they may
possess, from previous habits of life, for a service requiring a union of
courage, prudence, and discriminating observation - usually to be met with only
in individuals who have been thrown very much upon their own resources.
When the character of the country admits of it, the employment of such
individuals, singly, or in very small bodies, as scouts, is one of the most
available means of gaining intelligence of an enemy, without betraying the
secret of our own whereabouts.

Scouting (1861-1865)

Note: Listed below are examples of references to
"scouting" in the Wyman White book, references are also in the Gettysburg after
action reports of Trepp andStoughton.

Cavalry was used most often for gathering
information for the Army at the “Army” operational level. Regimental commanders
rarely had Cavalry available for reconnaissance at the “tactical” level. But
they still needed information about their area of operations. They had to use
men in their commands that could perform in this role; Berdan sharpshooters were
an obvious choice for these missions.

Deploying "Scouts" and “patrols” were necessary
to gain information about the terrain and to give early warning of enemy
presence and strength in their immediate area of operations.

The men chosen for "scouting" would have
undoubtedly been chosen because they had demonstrated the skills necessary for
performing in that role.

Wyman White book:

Chapter VIII – Chancellorsville Campaign, page
151: Monday May 11 – Through the
remainder of the month we lay in camp with the usual drill, inspections, and
parades and a great deal of picket duty, our regiment having the lion’s share of
it. Men from our regiment were often detailed to
go outside of the picket line to learn the whereabouts and movements of the
enemy.

Chapter XII – The Overland Campaign, page 227:
Battle of Wilderness – Our Corps, the
second, was first in line on the left of the Fredericksburg and Orange
Courthouse Pike which at this point runs in about a southwest direction towards
the courthouse. The plank road was very wide and in all probability was built
several years before in anticipation of a war with the people of the Northern
states.Our scouts, in moving along this plank road,
found that the enemy was in the woods in considerable force. General Hancock,
commander of our Corps, ordered our regiment to deploy as skirmishers and feel
for their position. We deployed, and in the dense woods, the advance was the
bugle call. We picked our way through the dense underbrush in a low swampy
place. Here we encountered a heavy Rebel picket line, driving it back on a heavy
support of infantry.

Cold Harbor, page 259:
Scouting – One afternoon the Major
commanding had orders to send a scouting party
of half a dozen men out to on the right of our lines as far as we
could go safely and observe the position and strength of the enemy in that
locality and report the same to our division headquarters. Five of our company,
including myself, was the detail. We started about two o’clock in the afternoon
and tramped on for at least mile after passing our pickets.

We noted everything
to the right and rear, the country there being mostly timberland.
After a while we struck a rebel scouting squad. We got the first shot and they
returned fire and rode off, they being mounted. Not one of us was hit and all
the rebels rode off as the distance was too great to expect results. After this
I thought it best to return to our lines as I thought the rebels would return
reinforced and they did do that.

Berdan's United States Sharpshooters in
the Army of the Potomac: by Capt.
C.A. Stevens, pages 269-270 -Chancellorsville:The regimental adjutant, Wm. H.
Horton, acting aid to Col. Berdan, was severely wounded in arm and side, while
with gun in hand he was rushing forward to capture some rebel scouts. He was
formerly the leader of our scouts at Yorktown, when
sergeant-major of the regiment. Once more he was performing the same duty,
having with him Wisconsin members: Jacobs, Albert Isham, Armfield, Stokes,
Alvord, and the present sergeant-major, Ben Atwell; some of whom served under
him at the former place.

Report of Lieut. Col. Casper Trepp,
First U.S. Sharpshooters, Battle of Gettysburg:
HDQRS. FIRST REGIMENT U.S.
SHARPSHOOTERS - July 29,
1863:

Early in the morning of July 2, this regiment was posted so, and with
instructions, to protect the left flank of the Third Corps. Soon thereafter
he
dispositions were changed, and I received an order to send 100 men on a reconnaissance in front of the right
of the Third Army Corps. This detachment I conducted in person,
and deployed them. The command was given to Capt. John Wilson, a very efficient
officer, and I returned to
the regiment. I
then received another order for 100 men for a reconnaissance.
Following the aide-de-camp, I conducted this second detachment directly
to and
followed the road in plain view of the enemy. This detachment might have been marched from the
original position to a point where the engagement
took place perfectly concealed
from view of the enemy and without loss of time.All this time
we were marching or halting in plain view of the enemy. For this violation of
rules of secret expeditions we paid dearly, for when we entered
the
woods, advancing as skirmishers, we met the enemy's skirmishers very soon
after crossing the road.

July 3.--Capt. J. H. Baker was
detached with the Fifth Army Corps, with Companies C, I, and K. The service they
performed was to protect batteries.
On this occasion, Corporal [Wellington] Fitch, of
Company C, distinguished himself by making a bold reconnaissance alone which
resulted in capturing
a squad of rebel sharpshooters that greatly annoyed our
artillery.

July 4.--the regiment was sent on
picket, but was soon recalled. While so posted, we lost 3 men wounded. In the
afternoon
Capt. John Wilson went
with 100 men on a reconnaissance. Nothing reported to
have happened worthy to be mentioned.

Report of Maj. Homer R. Stoughton,
Second U.S. Sharpshooters – Gettysburg:On the morning of July. 2, I was placed in line on the extreme
left
of the Third Corps, remaining there for nearly one hour, when the colonel
commanding instructed me to place my command in a position to cover a
ravine
near Sugar Loaf hill, which I did by putting Company H on the brow of the hill,
with vedettes overlooking the ravine, and Company D in the
ravine near the
woods, to watch the enemy's movements in that direction. Companies A, E, G, and
C formed a line perpendicular to the cross-road that
intersects with the
Emmitsburg I sent forward scouts to reconnoiter the ground.
I then rode out perhaps the distance of half a mile, and discovered
the enemy's
skirmishers advancing on my right, which, being unsupported by any connection
with skirmishers on my right, I was compelled to withdraw
to protect my flank.

Pitzer Woods –
Major General Daniel E. Sickles

Being positioned on low ground between the southern end of Cemetery Ridge and
the northern base of Little Round Top, had Third Corps commander,
Major General
Daniel E. Sickles, quite concerned about the situation that he and his command
was in. To make matters far worse, not only was the
Third Corps sitting on low
terrain, their front was dominated by a rise of high ground about 800 yards off
to the west. This put General Sickles and the
two divisions of his Corps in a
very precarious spot. The high ground to Sickles’ front meant that an enemy
force could move on his position out of the
sight of his main body, thus
creating a situation where the corps would have to rely on only a skirmish line
to give any advance warning of an intended attack.

Concerned and wanting to see what lay ahead of his corps, General Sickles
ordered a detachment of 100 men from the 1st U .S. Sharpshooters to be sent on a
reconnaissance. Companies B and G were sent out and posted by Lieutenant Colonel
Casper Trepp on a crest of ground west of the Emmitsburg road.
Although this
reconnaissance was completed, it failed to reveal any rebel activities along the
Third Corps line. This detachment would remain in their position
for the greater
part of the day exchanging small arms fire with Confederate pickets and
marksmen, withdrawing only after all of their ammunition had been consumed.

General Sickles ordered a second reconnaissance to be sent out. About midday a
detachment of 100 men from Companies D, E, F, and I, of the 1st U.S.
Sharpshooters, along with the 3rd Maine infantry acting as a reserve,
numbering 196 in the ranks, were sent out to discover any enemy force that was
positioned in front of the Third Corps

.

Throughout the war there was controversy and animosity between Colonel
Berdan and Casper Trepp. Due in part by the military incompetence of Berdan and
his unwillingness to command during battle, and the fact that Trepp was a
veteran soldier and proficient leader.

Because of Col. Berdan’s known history in battle, Capt. Briscoe of Birney’s
staff was sent along with Berdan to report on Col. Berdan’s performance.

Under the direct command of Colonel Berdan, the patrol moved south down the Emmitsburg road beyond Union lines and then deployed into a skirmish line
near a peach orchard. As they pushed on towards Pitzer’s Woods.

Shortly after entering the timber of the woods, the Sharpshooters struck the
skirmish line of the 11th Alabama. The rebels were driven back some 300 yards to
their main body under the accurate fire coming from the Sharpshooters’
breech-loading Sharps rifles. After forcing the enemy pickets out of the timber,
the Sharpshooters came upon the northwestern edge of the woods, revealing three
columns of infantry moving south through a six inch high corn field towards
the Union left. The Sharpshooters had run directly into Confederate Brigadier
General Cadmic M. Wilcox’ s brigade shuffling down Seminary Ridge in
preparation for the rebel attack that was planned to occur later in the day.

Berdan then ordered his men to “advance fire” and attack the nearest column of
rebel infantry. The result of the attack broke the ranks of the 11th Alabama and
sent the regiment into a confused run to the rear. It must be remembered that
the Sharpshooters’ detail numbered only around 100 officers and enlisted, yet
they
chose to contest the ground against nearly eleven-hundred. using their sharps
rifle and modern infantry tactics, the Sharpshooters had, in less than eight
minutes,
routed at least one of the rebels regiments.

During the fight, which only lasted about 20 minutes,
Berdan’s men took cover behind the rocks and trees of the woods, which offered
good protection from
Confederate
fire. The 3rd Maine being line infantry fought shoulder to shoulder
in line of battle, which did not allow them to use the surrounding terrain to
protect
them like the trained skirmishers of the 1st U.S. Sharpshooters.

The 3rd
Maine filled in the intervals between the trees and suffered heavily at Pitzer’s
Woods,
losing 48 men in killed or wounded as opposed to only 19 among the
Sharpshooters.

When Sickles first received reports from Colonel Berdan about the skirmish in
the woods, he was told that the Sharpshooters had encountered three columns
of rebel infantry moving south and to the east heading towards the army’s left
flank.

These three columns are often mistaken for the lead elements of General
Longstreet’s First Corps, Army of Northern Virginia, which ironically,
was moving south to assault and turn the left flank of the Army of the Potomac.
In truth, the troops that Hiram Berdan mistook for three columns of overwhelming
numbers, were the 8th, 10th, and 11th Regiments of Alabama Infantry.

It has been said that Berdan unveiled Longstreet’s intended attack on the Union
left, but the regiments he encountered were not even of Longstreet’s command.
The three regiments were of A. P. Hills Third Corps, Army of Northern Virginia,
and, were under the command of Brigadier General Cadmus Wilcox.

It was the intent of Wilcox’ s brigade to move into positions west of the
Emmitsburg Road to support Longstreet’s coming offensive.

After being told by Hiram Berdan that overwhelming numbers of enemy were
approaching, and convinced that an attack was forthcoming,
Dan Sickles felt that he and his corps had waited in their poor defensive
positions long enough. Up to this time he had received no decisive direction
from General Meade,
so acting on his own concerns and on the information gained by the Sharpshooters
and the 3rd Maine, General Sickles abandoned his assigned position in line and
moved the
Third Corps forward to the high ground that was in front of his position. He did
this to meet the assault that he and his aides thought the reconnaissance to
Pitzer’s Woods revealed.